This invention relates to an IC chip, a print apparatus, and a heat generation warning method.
A printer in a related art contains a motor driver for outputting a motor signal responsive to a control signal from a CPU to drive a carriage motor and a paper feed motor. The motor driver is implemented as a one-chip IC and a power supply voltage is supplied to one of a plurality of pins extending from a package. The motor driver is mounted on a board together with the CPU, memory, and a logic circuit.
This kind of motor driver has a thermal shutdown function to protect from heat generation. JP-A-6-225582, JP-A-8-501199, etc., discloses an example of a thermal shutdown circuit. If a carriage motor or a paper feed motor is over used and the internal temperature of the motor driver exceeds a threshold value (junction temperature), the thermal shutdown circuit operates for shutting down output of the motor driver. Accordingly, the carriage motor and the paper feed motor are stopped independently of the drive situation, and print processing and paper feed operation are forcibly terminated, thereby protecting the motor driver from heat generation.
However, in the protection method using the thermal shutdown function, the power of the motor driver is forcibly shut down at the shutdown time and thus the carriage motor and the paper feed motor are stopped independently of the print processing. Therefore, if the motor driver is cooled and is recovered from heat generation, it is impossible to resume the print processing at the shutdown point in time, and the print processing needs to be again performed from the beginning.
On the other hand, there is demand for reducing the cost of the motor driver. To meet the demand, the chip area may be lessened. However, if the chip area is lessened, the motor driver easily generates heat accordingly and the shutdown frequency is increased. If the shutdown frequency is thus increased, the print processing is forcibly terminated each time a shutdown occurs, interfering with smooth print processing. Thus, there is also a problem of incapability of lessening the chip area.